Magnetism Question 158
Question: Points A and B are situated along the extended axis of 2 cm long bar magnet at a distance x and 2x cm respectively. From the pole nearer to the points, the ratio of the magnetic field at A and B will be
[EAMCET 1984; CPMT 1986]
Options:
A) 4 : 1 exactly
B) 4 : 1 approx.
C) 8 : 1 exactly
D) 8 : 1 approx.
Show Answer
Answer:
Correct Answer: D
Solution:
For a magnet $ W _{1}=MB(\cos 0^{o}-\cos 90^{o})=MB( 1-0 )=MB $ (Nearly)
$ \Rightarrow \frac{B _{1}}{B _{2}}={{( \frac{x _{1}}{x _{2}} )}^{3}}={{( \frac{x}{2x} )}^{3}}=\frac{1}{8} $ (Approx.)
BETA
